二甲醚喷雾碰壁数值模拟与试验研究

Numerical Simulation and Experimental Research of DME Spray Wall-Impingement

基于离散液滴模型(DDM),结合柴油机实际工作情况,建立了喷雾碰壁的数学模型。将该模型与KIVA程序耦合,对多种形态的喷雾碰壁进行了模拟计算。在压力定容室内,利用高速摄影机对二甲醚(DME)和柴油进行了喷雾碰壁的试验研究。将模拟与试验结果进行了对比分析,并考察了碰壁角度、碰壁距离等对DME碰壁过程的影响。获得了DME喷雾碰壁特性的一般规律;在同样条件下,DME喷雾体的壁面扩展度和油膜厚度均比柴油小,说明DME比柴油蒸发速度快,雾化质量好。

A mathematic model of spray wall-impingement was established based on discrete droplet model （DDM） considering the operating conditions of diesel engine. The model was then coupled with KIVA program and various forms of spray wall-impingement were numerically simulated. The spray wall-impingement experiments of dimethyl ether （DME） and diesel were carried out in a constant volume chamber by using a high speed camera. Results of simulations and experiments were compared and analyzed with emphasis placed on influence of impinging angle, impinging distance, etc. , on the wall-impingement characteristics of DME. The general characteristics of the wall-impingement of DME were then obtained. It＇s showed that both of the wall spread distance and the liquid film thickness of DME are smaller than those of diesel under the same conditions, which indicate that DME possesses faster evaporation rate and better atomization quality.